Universal compatibilizing agent for polyolefines and polar plastics

ABSTRACT

Product, method and use of a copolymer AB as a compatibilizing agent between a polar thermoplastic polymer C and a polyolefine D. The method of making AB comprise the steps of: a) melting a copolymer (A) comprising a larger amount of methylmethacrylate units and a smaller amount of functional vinyl or (meth)acrylate units wherein functional moiety is selected in the group consisting of (a hydroxyl, a carboxylic, a glycidyl or an amine functional group); together with maleic anhydride grafted polypropylene (B) allowing condensation reaction to occur between the functions under “A” and the anhydride under “B”; b) the condensation copolymer obtained under a) is further melt together with the two polymers C and D to be homogenized, or melt processed as an interlayer between the two molten polymers.

This is a nationalization of PCT/EP01/10444, filed Sep. 10, 2001andpublished an English, which claims the benefit of provisional 60/231,902filed Sep. 11, 2000.

Promoting the adhesion between two immiscible polymers has been aconcern of increasing interest. Most useful applications are polymeralloying in very fine dispersion of one polymer into the other, andlaminated structures and profiles obtained by coextrusion orcolamination for example.

Various solutions have been proposed to induce some degree ofinterfacial bonding between two polymers exhibiting no or poor mutualadhesion. Among others, a favorite route is interleaving a thirdpolymeric component whose segments provide good spontaneous adhesionwith either component respectively. Master examples are di-blockcopolymers made by anionic polyaddition [references: S. H. Anastasiadis,I. Gancarz and J. T. Koberstein, Macromolecules 1989, 22, 1449-1453; C.Creton, E. J. Kramer, C.-Y. Hui and H. R. Brown, Macromolecules 1992,25, 3075-3088]. Unfortunately, none of the existing commercial blockcopolymers is suitable to provide enough bonding strength between apolyolefine D such as polypropylene and a polar polymer C such aspolyvinyl halide, polyvinylidene halide, poly(meth)acrylate, polyester,or polycarbonate.

It has been found surprisingly that a suitable compatibilizing agent ABof binary or ternary mixtures comprising at least one compound of thetwo above cited series of polymers C and D, can be obtained by thefollowing way:

-   -   i. A copolymer (A) comprising a larger amount of        methylmethacrylate units and a smaller amount of functional        vinyl or (meth)acrylate units wherein the functional moiety is        characterized as being a hydroxyl, a carboxylic, a glycidyl or        an amine functional group.    -   ii. The copolymer A described under “i” is melt processed        together with maleic anhydride grafted polypropylene (B)        allowing condensation reaction to occur between the functions        under “i” and the anhydride under “ii”.    -   iii. The new segmented multiblock copolymer obtained under “ii”,        is further melt processed together with the two polymers C and D        to be homogenized, or melt processed as an interlayer between        the two molten polymers.

Accordingly, the present invention provides a method of making acopolymer AB as a compatibilizing agent between a polar thermoplasticpolymer C and a polyolefine D comprising the steps of:

-   -   a) melting a copolymer (A) comprising a larger amount of        methylmethacrylate units and a smaller amount of functional        vinyl or (meth)acrylate units wherein functional moiety is        selected in the group consisting of (a hydroxyl, a carboxylic, a        glycidyl or an amine functional group);    -   together with maleic anhydride grafted polypropylene (B)        allowing condensation reaction to occur between the functions        under “A” and the anhydride under “B”;    -   b) the condensation copolymer obtained under a) is further melt        together with the two polymers C and D to be homogenized, or        melt processed as an interlayer between the two molten polymers.

In a preferred embodiment of the invention, the copolymer A contains0.02 to 6 (x) mole percent of structural units bearing the functionalgroup, the grafted copolymer B contains from 0.2 to 3 (y) mole percentof maleic anhydride units, the ratio of copolymer A and graftedcopolymer B in the multiblock copolymer AB is such that the ratio x overy lies between 10 and 1 and preferably between 6 and 2.

In another preferred embodiment of the invention, the copolymer Acontains between 0.1 to 6 mole percent of 2-hydroxyethyl(meth)acrylateand its weight average molecular weight (measured as PS equivalentmolecular weight) is between 40000 and 500000 g/mol, preferably between150000 and 500000 g/mol.

The copolymer A is easily obtained for example by solutionpolymerization in a suitable solvent such as methylethylketone (MEK),using a thermal initiator.

The present invention also provides a use of copolymer AB as definedabove as a compatibilizing agent between a polar thermoplastic polymer Clike polyvinyl halide homo or copolymer, polyvinylidene halide homo orcopolymer, poly(meth)acrylate, polyester, or polycarbonate and apolyolefine D as single polymer or in blend with other polyolefines.

Polyolefine D can be polypropylene homo or copolymer with one of moreco-monomer and made either with Ziegler-Natta catalyzer or with singlesite catalyzer. Polypropylene copolymer can have random or multisequencestructure including the reactor made copolymer known as block copolymer.

Polyolefine D can also be a homo polyethylene or a co-polyethylene withzero to 50 wt % of a co-monomer with a number of carbones from 3 to 20.

Endly polyolefine D can be a blend of a polymer D defined above with apolyolefinic rubber like EPDM, butyl rubber, BR, SBR.

Maleic anhydride grafted polypropylene is available in various gradesand can be supplied by DuPont under the trademark FUSABOND®, by Exxonunder the trademark EXXELOR®, by Uniroyal under the trademark POLYBOND®,by Atofina under the trademark OREVAC™ for example.

EXAMPLE 1

In a 2 liter stirred reactor, 840 g of methylethylketone, 274 g ofmethylmethacrylate, 6 g of 2-hydroxyethylmethacrylate (HEMA) and 2.8 gof azobis(isobutyronitrile) are introduced. The oxygen is removed byflushing dry nitrogen in the solution, The temperature is raised to 66°C. The solution is reacted over 24 hours at 66° C. An additional 1.4 gof azobis(isobutyronitrile) is added to the solution and the reaction iscarried on during 12 more hours. The copolymer is recovered byprecipitation of the solution in deionized water as non solvent and thendried. The yield obtained is 95% for the methylmethacrylate and 100% forthe HEMA. The copolymer is characterized 5 by weight average molecularweight of 152000 g/mol as measured by gel permeation chromatography.

The reactive melt processing leading to the copolymer AB is carried onby mixing 200 g of copolymer A, as prepared following the abovedescription, and 100 g of copolymer B, FUSABOND® MD-353D, on a two rollmill at 180° C. during 30 minutes.

Sandwich elements consisting of a polypropylene sheet (1 mm thick) and apolyvinylidene fluoride sheet (2 mm thick) are bonded with a thin film(100 microns thick) of copolymer AB. The sandwiches are bonded bypressing the above construction during 15 minutes at 150° C. Theadhesion between the two sheets is tested by means of a U-peel test(reference: S. Wu, Polymer interface and adhesion, M. Dekker Inc., NewYork, 1982). A fracture energy (G) of 1607 J/m² has been measured.

EXAMPLES 2 TO 5

In the example 2 to 4, the same experimental procedure as described inthe example 1 has been followed. The HEMA amount introduced in thecopolymer A is varied (see the following table) as well as the weightaverage molecular weight, by means of a transfer agent(dodecanethiol-DDT). The measured fracture energies (G) are given foreach example.

mol % Mw Example HEMA in wt % (g/mol) of number copolymer A DDT^(a)copolymer A x/y G (J/m²) 2 1.68 0.49 94000 2.3 1036 3 1.76 0.17 2220002.4 1513 4 5.09 0 172000 5.4 1659 5: without — — — — 63 copolymer^(a)This percentage is relative to the initial total mass of monomersused in the synthesis of copolymer A.

EXAMPLE 6

The blending of polyvinylidene fluoride with polypropylene is evaluatedwith and without using the copolymer AB. In particular, the blend of 19weight percent of polyvinylidene fluoride, 76 weight percent ofpolypropylene and 5 weight percent of a copolymer AB (copolymer number 5in the table presented above) prepared on a two roll mill (rolldiameter: 110 mm; temperature: 180° C.; roll speed: 15 rpm; gap: 1 mm)leads to a two phase material presenting particles whose diameter rangesbetween 3 and 10 μm whereas the blending of polyvinylidene fluoride andpolypropylene without copolymer displays particles characterized by alarger diameter, between 15 and 80 μm.

1. Method of making a copolymer AB as a compatibilizing agent between apolar thermoplastic polymer C and a polyolefine D comprising the stepsof: a) melting a copolymer A comprising a larger amount ofmethylmethacrylate units and a smaller amount of functional vinyl or(meth)arcylate units wherein functional moiety is selected in the groupconsisting of a hydroxyl, a carboxylic, a glycidyl and an aminefunctional group; together with maleic anhydride grafted polypropylene Ballowing condensation reaction to occur between the functions under “A”and the anhydride under “B”, b) the condensation copolymer obtainedunder a) is further melt together with the two polymers C and D to behomogenized, or melt processed as an interlayer between the two moltenpolymers.
 2. Method according to claim 1 wherein the copolymer Acontains 0.02 to 6 (x) mole percent of structural units bearing thefunctional group, the grafted copolymer B contains from 0.2 to 3 (y) molpercent of maleic anhydride units, the ratio of copolymer A and graftedcopolymer B in the multiblock copolymer AB is such that the ratio x overy lies between 10 and 1 and preferably 6 and
 2. 3. Method according toclaim 2 wherein the copolymer A contains between 0.1 to 6 mole percentof 2-hydroxyethyl(meth)acrylate and its weight average molecular weightis between 40000 and 500000 g/mol, preferably between 150000 and 500000g/mol.
 4. A method of using copolymer AB obtained by the methodaccording to claim 1 as a compatibilizing agent between a polarthermoplastic polymer C and a polyolefine D comprising the step ofmelting the copolymer AB together with the polymers C and D to behomogenized or melt processed as an interlayer between the moltenpolymers C and D.
 5. The method of using copolymer AB according to claim4 wherein the polyolefine D is a polypropylene homo or a copolymer withone or more co-monomer.
 6. The method of using copolymer AB according toclaim 4 wherein the polyolefine D is a homo polyethylene or aco-polyethylene with zero to 50 wt % a co-monomer with a number ofcarbon from 3 to
 20. 7. The method of using copolymer AB according toclaim 4 wherein the polyolefine D is a blend with a polyolefinic rubber.8. The method of using copolymer AB according to claim 7 with a rubberphase partially or fully crosslinked.
 9. The method of using copolymerAB according to claim 4 with additive like inorganic filler and wellknown polymer stabilizers.
 10. Copolymer AB obtained by the methodaccording to claim 1.